The present invention relates generally to light fixtures and, more particularly, to light fixtures suitable for illuminating flat surfaces.
Surface illuminating devices are well known for indoor and outdoor uses. For example, light fixtures are used in museums to illuminate paintings and other works of art. In the outdoor environment, illumination features are found in general use illuminating highway signage and advertising media such as poster boards and bulletins as discussed more fully in U.S. Pat. No. 6,168,295, incorporated herein by reference. For convenience of discussion, where the term xe2x80x9cbillboardxe2x80x9d is used herein, it is meant to encompass both poster boards and bulletins.
While this specification sets forth the present invention as it relates to techniques of illuminating outdoor signage, it will be recognized that the present invention has application to a variety of cases wherein it is desirable to illuminate large flat surfaces.
In the case of billboards, these popular devices display graphic advertisements or public service messages and the boards are disposed so as to be seen by motorists passing them during travel. Typically, they are illuminated from below by one or a plurality of spaced light fixtures disposed along a bottom surface of the sign. An important desirable characteristic of such fixtures is that, they cooperate to provide uniform lighting to the sign so that no dark spots or shadows occur across the surface thereof. This characteristic is sometimes not found in conventional sign lighting fixtures.
Thus, it is not uncommon in some outdoor illuminating systems utilizing a plurality of conventional light fixtures, to find islands of bright illumination having shadowed areas at the periphery of the islands and between the islands of light. The result is an illuminated sign that is not esthetically attractive and which, in some respects, fails to convey an advertiser""s message because of uneven illumination or shadows on the board.
The case can be more serious in highway signage wherein uneven or poor highway sign illumination can present serious safety problems, especially to the traveler unfamiliar with the terrain or during adverse weather conditions.
Thus, there is a need for a light fixture, adapted for use in illuminating flat outdoor surfaces such as highway signs and billboards that can illuminate the respective surfaces in a bright and generally uniform manner, thereby substantially reducing shadowed areas.
It will be recognized, of course, that in view of the environment in which the device is utilized, such a light fixture should have weather resistant capabilities since it will be exposed to a variety of changing and, sometimes severe, weather conditions. It should be resistant to invasion by insects and other pests and it should be easily maintained and capable of being opened quickly and easily for lamp replacement and maintenance. In addition, the light fixture should have good aerodynamic characteristics so as to withstand high winds without damage.
Further, the fixture should not contribute to xe2x80x9clight pollutionxe2x80x9d by scattering light away from the object being illuminated. Still further, the light fixture should have a low profile so that it would not draw the eye of the observer to itself but, instead, would induce the observer to look at the surface being illuminated.
As stated above, in some cases, conventional light fixtures fail to satisfy the aforesaid criteria.
In view of the foregoing, there is a need for a light fixture having a low profile, readily accessible for repair and lamp replacement and aerodynamically shaped to help reduce wind damage. Desirably, such a light fixture would be capable of providing a broad spectrum of illumination over a flat surface so that, when used singly or in combination with similar fixtures, a large surface could be illuminated in a relatively uniform manner. Ideally, such a light fixture would be low in cost to manufacture, being constructed of readily available materials.
Desirably a light fixture having the above-described characteristics could be manufactured also in kit form for installation in existing, conventional fixtures thereby enabling low cost retrofits of such fixtures.
In accordance with the present invention, there is provided a light fixture suitable for illuminating highway signage and billboards having large surface areas. The fixture includes a curved reflector assembly, shaped generally like a cobra hood that is attached to a plate disposed in a base. The reflector assembly 38 includes a plurality of spectral segments, integrally disposed in bands and rows of the reflector assembly so that an portion of the spectral segments is disposed above the plate, an intermediate portion of the spectral segments is disposed partially above and partially below the plate, and a portion of spectral segments is disposed below the plate surface. A lamp is supported within the fixture for facilitating projecting a substantially rectangularly shaped plane of light distributed in a plurality of substantially rectangularly shaped luminance patterns onto a flat surface. In one embodiment, an induction lighting assembly is utilized in cooperation with the reflector assembly to provide uniform surface illumination at relatively low energy usage rates. A retrofit kit, for upgrading conventional light fixtures, is provided.
The present invention affords several advantages. For example, the light reflector assembly includes a plurality of highly polished, spectral segments that cooperate to distribute light over a flat surface uniformly, in an efficient and energy conserving manner. When highway signage and billboards are illuminated by the present invention, shadows and dark spots are substantially reduced and an aesthetically pleasing result is obtained.
In addition, the incorporation of an inductance lighting assembly into the light fixture results in substantially increased system life and improved performance. This is accomplished while energy costs are reduced. Further, as a result of modifying the light fixture of the present invention, retrofit kits can be utilized to modify conventional fixtures. In some cases, modification can be accomplished in the field without the necessity of removing the pre-existing fixture. Thus, older fixtures can be made more efficient at relatively low cost. Since portions of the old fixtures are conserved, additional cost savings are realized.
The light fixture of the present invention is constructed of readily obtainable materials and it has a rugged construction for use in varying weather conditions. The provision of a light shield helps to reduce unwanted light pollution and, as a result, the fixture is usable in an urban environment. In addition, the light fixture of the present invention is easy to install, mechanically simple, economical and easy to maintain and service.
Other aspects and advantages of the present invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the invention.